The present invention relates generally to the field of olefin polymerization catalysis, metallocene catalyst compositions, methods for the polymerization and copolymerization of olefins, and polyolefins. More specifically, this invention relates to dual catalyst systems for producing broad or bimodal molecular weight distribution polyolefins in the absence of added hydrogen.
Broad or bimodal molecular weight distribution polyolefins (homopolymers, copolymers, terpolymers, and the like) can be produced using various combinations of catalyst systems and polymerization processes. Such broad or bimodal molecular weight distribution polyolefins may be produced using a dual metallocene catalyst system, but often requiring the presence of added hydrogen in order to do so. The addition of hydrogen gas to certain polymerization reactor systems, however, may adversely affect reactor operating conditions, as well as the resulting properties of the polymer produced, for example, polymer molecular weight or melt index.
It would be beneficial to produce broad or bimodal molecular weight distribution polyolefins using a metallocene-based dual catalyst system that does not require the addition of hydrogen to the polymerization reactor. Accordingly, it is to this end that the present invention is directed.